If the intent is to create a large string, '' x 1024 x 1024 x 256 isn't working:

C:\test>perl -wle "$x='' x 1024 x 1024 x 256; print length( $x )"
0
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A null string isn't the same a string containing a null. And 0 * anything is 0. Try

C:\test>perl -wle "$x = chr(0) x 1024 x 1024 x 256; print length( $x )
+"
268435456
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Personally, I find even that a little dubious in that, due to precedence, it creates the final string in 3 stages rather than 1. I think that

C:\test>perl -wle "$x = chr(0) x (1024* 1024 * 256); print length( $x 
+);<>"
268435456
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is 'better', though it has little effect on the outcome.